1. Field of the Invention
The present invention relates to testing apparatus generally and particularly to testing apparatus for testing labyrinth passageways formed in a disk stack of a disk valve for proper labyrinth resistance to fluid flow.
2. Description of the Prior Art
High energy loss in pressurized fluids is usually provided by disk stacks having a central inlet for fluid flow and a peripheral outlet for fluid exhaust. The inlet and outlet could also be reversed. The disk stack has individual disks which subdivide the fluid into a plurality of individual streams in respective passageways which passageways provide a labyrinth type tortuous multi-turn path having a large length to diameter ratio to impart high frictional resistance losses to the fluid flow as it flows between the inlet and the outlet of the disk stack. The tortuous paths of the disk stack may be provided by individual disks having the tortuous path etched onto the face of each disk to allow a multi-turn flow of the fluid with the turns being confined to the face of the disk. An example of such a high energy loss disk may be found in U.S. Pat. No. 3,514,074. The tortuous paths may also be formed by placing together a series of perforated disks to provide for multi-turns of the fluid between the faces of the stacked perforated disks. An example of such a disk stack may be found in U.S. Pat. No. 3,513,864.
During manufacture of such mentioned disk stacks it will be understood that perforated disks may be improperly aligned into the stack thereby preventing flow between the planes of adjoining disks and a blocked condition may arise. Also etching may be improperly performed on etched disks resulting in either blocked or open labyrinths. Also after long term operation of the disks stack dirt particles and other contaminants may get trapped and build up within the labyrinths to eventually restrict the passageways making certain disks of the disk stack inoperative. Thermal differentials may also cause some of the disks to warp providing short circuits across the labyrinths and an ineffective disk stack.
Since the disk stack is either bolted together or brazed into a single unit, it is highly desirable to know whether the individual disks of the disk stack are operative or inoperative and if operative, whether the energy loss provided by the individual disks is within an acceptable range. To date, the only check on individual disks had to involve the disassembly of the disk stack once its overall operation was suspected and the replacement of the individual disk stacks which proved faulty. A device was needed which could determine which disks were faulty in a stack to evaluate need for repair or replacement and for possible in-stack repair.